EVIDENCE ON HEREDITARY OCCURRENCE OF PLACENTAL ANASTOMOSES IN HETEROSEXUAL TWINS IN SHEEP

Pedigree analysis of 22 heterosexual litters demonstrating the leukocy te chimerism (XX/XY) was carried out. The analysis revealed the famili al occurrence of the chimerism in 15 litters. Eight litters were obtai ned from four ewes and the other seven ones were sired by three rams. Moreover, it was shown that ten chimeric litters had a common male anc estor. The coefficients of inbreeding ranged from 0.0 to 0.0625, with a mean of 0.019. These results suggest that the development of placent al anastomoses in sheep is genetically controlled. A possible mode of the genetic control is discussed.